RARE PLANT SURVEY REPORT GRADY RANCH, MARIN COUNTY, CALIFORNIA September 2011 Prepared for: Skywalker Properties Ltd. 5858 Lucas Valley Road Nicasio, CA 94946 Prepared by: WRA, Inc. 2169-G East Francsico Blvd. San Rafael, California 94901 TABLE OF CONTENTS 1.0 INTRODUCTION........................................................... 1 1.1 Study Area Description................................................ 1 1.1.1 Vegetation................................................... 1 1.1.2 Soils. ...................................................... 5 2.0 METHODS................................................................ 6 2.1 Background Data. ................................................... 6 2.2 Previous Studies..................................................... 7 2.3 Field Survey. ....................................................... 8 3.0 RESULTS................................................................. 8 3.1 Background Data Search Results........................................ 8 3.2 Field Survey Results. ................................................ 1 1 4.0 CONCLUSION............................................................ 1 1 5.0 REFERENCES. .......................................................... 1 2 LIST OF FIGURES Figure 1. Study Area Location Map................................................ 2 Figure 2. Biological Communities Observed in the Study Area. 3 Figure 3. Study Area Soils Map and Special Status Plant Occurrences. 9 LIST OF APPENDICES Appendix A - List of Observed Plant Species Appendix B - Potential for Special Status Plant Species to Occur in the Study Area i 1.0 INTRODUCTION This report presents the results of focused plant surveys conducted on the Grady Ranch property (Study Area) northwest of the City of San Rafael, Marin County, California (Figure 1). The Grady Ranch Property is located on Lucas Valley Road, approximately four miles west of U.S. Highway 101. The purpose of the survey was to update a previous survey performed on the Grady Ranch site in the early 1990s. The surveys were conducted on March 17, May 31, and August 18, 2011 and consisted of six person-days of surveys, or approximately 50 person-hours. No special status plant species were observed within the Study Area. However, one special status plant, Tiburon buckwheat (Eriogonum luteolum var. caninum, CNPS List 1B) was observed approximately 200 feet north of the Study Area, on the larger Grady Ranch property. This report updates a previous biological resources assessment and rare plant survey conducted by LSA in 1992 for preparation of the 1992 EIR (Nichols-Berman 1996). 1.1 Study Area Description The 109-acre Study Area represents approximately 46 percent of the larger Grady Ranch Property, and is bounded by Lucas Valley Road to the south, and the Grady Ranch Property boundary to the east. The Study Area boundaries to the north and west were placed in order to encompass the total area of potential impacts under the proposed development project and do not represent the Grady Ranch Property boundary. The Study Area includes open space consisting of vegetation communities including bay/oak woodland and native perennial and non-native annual grasslands. Land uses adjacent to the Study Area include a low-density residential development to the east, open space/rural development to the south, and open space to the north and west on the remainder of the Grady Ranch Property. Elevations range from approximately 70 to 150 meters. A more thorough discussion of the biological communities that occur in the Study Area is included below. 1.1.1 Vegetation Table 1 summarizes the area of each biological community type observed in the Study Area. Biological communities in the Study Area include non-native annual grassland, oak-California bay woodland, riparian wetlands, Central Coast riparian scrub, seasonal freshwater emergent wetlands, perennial freshwater emergent wetlands and Valley needlegrass grassland. Descriptions for each biological community are contained in the following sections. 1 Sonoma Napa County County Solano County Detail Marin County Area Contra Costa County Alameda County San Francisco County Study Area Lucas Valley Rd. Figure 1. Study Area Location Map Date: September 2008 Grady Ranch 0 0.25 0.5 Image Source: USGS Topo Quad Map By: Derek Chan Marin County, California Miles Filepath: l:\ACAD2000\18076\GIS\ArcMap\Fig1_LocMap.mxd Matchline Detail Area Study Area Miller Creek Legend Study Area Valley Needlegrass Grassland Matchline Central Coast Riparian Scrub Potentially Jurisdictional Waters of U.S. Top of bank Wetlands Riparian Seasonal freshwater Perennial freshwater Rare Plants Tiburon buckwheat (100 individuals) Figure 2a. Biological Communities and Observed Rare Plants within the Grady Ranch Study Area . Date: September 2011 Image Source: Marin County, 2004 Grady Ranch 0 200 400 Map By: Derek Chan Feet Filepath: L:\Acad 2000 Files\18000\18076\ Marin County, California GIS\ArcMap\BRA\Fig2_VegComm.mxd Non-Native Annual Grassland Non-native annual grassland is an herbaceous plant community dominated by annual grasses that are not native to California. Grass species found in this community within the Study Area include Italian ryegrass (Lolium multiflorum), rat-tail fescue (Vulpia myuros), ripgut brome (Bromus diandrus), rattlesnake grass (Briza maxima), wild oats (Avena sp.), soft brome (Bromus hordeaceus) and harding grass (Phalaris aquatica). Annual and perennial wildflowers and forbs also occur in this biological community, including yarrow (Achillea millefolium), clover (Trifolium spp.), California poppy (Eschscholzia californica), filaree (Erodium spp.), lupine (Lupinus spp.), Non-native annual grassland is located throughout the Study Area on slopes and ridges. Oak - California Bay Woodland A variant of the woodland communities described in Holland (1986) occurs throughout the Study Area along and surrounding the drainages. Dominant tree species in Study Area woodlands were California bay (Umbellularia californica) and coast live oak (Quercus agrifolia). The density of trees and canopy cover varied throughout the site, with the densest stands having a sparse understory dominated by leaf litter and the most open stands having an understory of non-native annual grassland. Riparian Wetlands Riparian wetland plant communities are not described in Holland (1986), but occur within floodplains of rivers, creeks, and streams. Approximately 0.017 acres of wetlands found within the floodplain of Miller Creek were mapped within the Study Area. These wetlands were observed on gravel bars within the bed of Miller Creek, directly abutting the active stream channel. These wetlands generally had a dense overstory of either riparian scrub or mixed oak-bay woodland, and were dominated by woody and herbaceous wetland species including arroyo willow (Salix lasiolepis), California blackberry (Rubus ursinus), stinging nettle (Urtica dioica), horsetail (Equisetum arvense), and mugwort (Artemisia douglasiana). Central Coast Riparian Scrub This community is described as a scrubby streamside thicket, varying from open or impenetrable, dominated by willows (Holland 1986). Riparian scrub in the Study Area occurred in patches along Miller Creek and its tributaries (Figure 2). Dominant vegetation in riparian scrub communities included arroyo willow (Salix lasiolepis) and California blackberry (Rubus ursinus). Seasonal Freshwater Emergent Wetlands Seasonal wetland plant communities are not described in Holland (1986), but occur in swales and depressions that are ponded or saturated during the rainy season for sufficient duration to support vegetation adapted to wetland conditions. Seasonal wetlands in California are highly variable in plant composition, depending on the length of ponding or inundation. They also generally lack the plant community assemblage typical of defined marshes and vernal pools. Approximately 0.028 acres of seasonal wetlands were found in the Study Area (Figure 2) in a vegetated depression that collects flows from an ephemeral drainageway during the rainy season. This community was dominated by iris-leaf rush (Juncus xiphioides) and rattlesnake grass (Briza maxima). 4 Perennial Freshwater Emergent Wetlands Approximately 0.037 acres of perennial freshwater emergent wetlands, or seep wetlands, were mapped within the Study Area (Figure 2). Seep wetlands occur in areas where subsurface water flow daylights, and soils remain perennially saturated and support vegetation adapted to wetland conditions. Seep wetlands within the Study Area were dominated by sedges (Carex sp.), giant chainfern (Woodwardia fimbriata), seep monkeyflower (Mimulus guttatus), tall flatsedge (Cyperus eragrostis), and Douglas iris (Iris douglasiana). Valley Needlegrass Grassland Valley needlegrass grassland is a mid-height (to two feet) grassland dominated by perennial, tussock forming needlegrass (Nassella pulchra) with native and non-native annuals occurring between the perennials and often exceeding the bunchgrasses in cover (Holland 1986). This community occurred primarily in the northeastern portion of the Study Area in stands varying in cover of needlegrass (Figure 2). Approximately 2.9 acres of valley needlegrass grassland were mapped in the Study Area. Non-native grasses and other species typical of non-native annual grassland were intermixed with the needlegrass. 1.1.2 Soils The USDA Soil Survey for Marin County (USDA 1985) indicates that the Study Area has three native soil types: Blucher-Cole complex, 2 to 5 percent slopes; Saurin-Bonnydoon